238 SCIENCE PROGRESS 



observations which suggest the question whether this base or 

 one closely related to it be not sometimes produced by a fer- 

 mentative process within the tissues of the animal. These 

 observations are connected with the phenomenon of anaphy- 

 laxis. On introducing into an animal a very small quantity 

 of a protein derived from another species, the animal, after the 

 lapse of several days, becomes extremely sensitive to further 

 injections of the protein and this sensitiveness is retained 

 during a very long period. Thus a guinea-pig which has 

 received an injection of a few hundredths of a cubic centimetre 

 of horse serum will, after the lapse of seven to ten days, be 

 killed very rapidly by an interperitoneal or intravenous injec- 

 tion of 5 c.c. of the same serum. On the other hand such an 

 injection would not produce serious results in a guinea-pig 

 which had never been treated with horse serum, so that 

 anaphylaxis had not been produced in it. Now, the remark- 

 able thing is that death caused by anaphylactic shock is closely 

 similar to death produced by an injection of /3-iminazolylethyl- 

 amine, as was pointed out recently by Dale and Laidlaw. 

 Whether an anaphylactic guinea-pig be given a small injection 

 of horse serum or a normal animal an injection of i milli- 

 gram of /3-iminazolylethylamine, in either case the animal dies 

 very rapidly from an acute valve-like constriction of the bron- 

 chioles which produces asphyxia ; after death, the lungs are 

 distended and spongey. Another point of similarity is the 

 extraordinary lowering of the body temperature, which may 

 be as much as io . 1 The resemblance of anaphylactic shock to 

 poisoning with the amine is not confined to guinea-pigs, which 

 are very sensitive in this respect. In dogs the action is not so 

 violent, yet very similar in the two cases. The only points of 

 difference are that /3-iminazolylethylamine does not cause 

 bleeding of the intestine, nor does it render the blood in- 

 coagulable as is the case in anaphylactic shock (and also in 

 poisoning by an injection of peptone). The mechanism of 

 anaphylaxis is still obscure ; it has been suggested that the 

 first sensitising injection leads to the production of a ferment, 



1 Quite recently Pfeiffer has shown that the similarity extends even further. 

 Very minute doses of protein produce fever in an anaphylactic animal, instead of 

 a fall of temperature. Now very minute doses of iminazolylethylamine also 

 produce fever. Pfeiffer considers that the base in question will prove of 

 importance in solving the problem of anaphylaxis. 



